Syrian President Bashar Assad issued a general amnesty Tuesday for prisoners who committed political "crimes." Syrian state television said the amnesty covered "all members of political movements," including the outlawed Muslim Brotherhood.

The Syrian state TV report said the amnesty covers "crimes committed before May 31" and reduces criminal sentences for felony convictions in half unless a personal lawsuit is involved.

In Washington, the Obama administration voiced doubts over the amnesty offer.

"He's said a lot of things in recent weeks and months, but we've seen very little concrete action," State Department spokesman Mark Toner was quoted as saying by the AP.

Earlier Tuesday, Mohammad Said Bkheitan, assistant secretary general of the ruling Baath party, said mechanisms for a national dialogue would be announced within the next 48 hours. According to Bkheitan, it was "premature" to talk about constitutional changes that would allow challenges to Assad in the 2014 presidential election.